This invention relates to herbicide extenders, herbicidal compositions, and herbicidal methods. In particular, this invention is addressed to the problem of herbicidal degradation occurring in certain soils.
Thiocarbamates are well known in the agricultural art as herbicides useful for weed control in crops such as corn, potatoes, beans, beets, spinach, tobacco, tomatoes, alfalfa, and rice. Thiocarbamates are primarily used in pre-emergence application, and are particularly effective when incorporated into the soil prior to the planting of the crop. The concentration of the thiocarbamate in the soil is greatest immediately after application of the compound. How long thereafter the initial concentration is retained depends in large part on the particular soil used. The rate at which the thiocarbamate concentration declines following its application varies from one type of soil to the next. This is evident both in the observable extent of weed control and in the detectable presence of undegraded thiocarbamate remaining in the soil after considerable time has elapsed.
It is therefore an object of this invention to increase the soil persistence of thiocarbamate herbicides and thus improve their herbicidal effectiveness.